1. Field of the Invention
The present invention relates to a tantalum chip type capacitor device used for a portable device or the like (e.g., telephone).
2. Related Art
A tantalum chip type capacitor device has been used for a power source circuit for a portable device (e.g., telephone, laptop computer) requiring a large capacity. In the future, an increasingly miniaturized, thin-shaped and lighter weight tantalum chip type capacitor device will be demanded.
FIG. 8 is a cross-sectional view illustrating a capacitor element used for the tantalum chip type capacitor device.
As shown in FIG. 8, the capacitor element 1 is made in such a manner that tantalum (Ta) 2 in the form of metal powders and a tantalum bar 3 that works as an anode terminal are subjected to pressurization, molding and vacuum hardening, and in the surface thereof, a tantalum oxide film (Ta2O5) 4 used as a dielectric body is formed by electrochemical anodization.
As an electrolyte, a solid manganese dioxide layer (MnO2) 5 is formed thereon by the thermal decomposition of manganese nitrate. In order to allow this manganese dioxide layer 5 to have thereon an electric connection, a graphite layer 6 is provided. On the graphite layer 6, a cathode lead 8 is formed by use of a silver covering material 7 and a conductive adhesive agent.
FIG. 9 is a schematic view of a conventional tantalum chip type capacitor device using the capacitor element 1. The anode terminal 9 which is bent in the shape of an overturned letter U is welded to the tantalum bar 3 of the capacitor element 1 provided as described above at a welding point 10. The cathode terminal 11 bent in a complicated manner is pressure-bonded to the cathode lead 8 formed of a conductive adhesive agent. Furthermore, the capacitor element 1, the anode terminal 9, and the cathode terminal 11 are partially exposed to the exterior to be molded by an epoxy resin 12, thereby forming the chip tantalum capacitor.
As described above, bent and intricately-shaped electrode elements have been used for an anode terminal and a cathode terminal of conventional tantalum chip type capacitor devices, thus requiring man-hours and cost. Additionally, bent and intricately-shaped electrode elements have been used, therefore, miniaturized, lighter weight and thin-shaped chip capacitors were not achieved.